ZAO (ZnO:Al) transparent conductive thin films have been prepared by middle-frequency alternative magnetron sputtering with ZAO (98 wt % ZnO + 2 wt.% Al2O3) ceramic target. The influences of substrate temperature on the microstructure, optical, and electrical performances of ZAO films have been studied. UV-Vis and Van der Pauw investigated the visible transmittance, carrier concentration, and Hall mobility, respectively, while microstructure has been characterized by X-ray diffraction (XRD). The results show substrate temperature is a dominant factor for microstructure, optical, and electrical performances of ZAO thin films. The lowest resistivity obtained in this study was 4.6 x 10(-4) Omega CM for the film with sheet resistance of 32 Omega, which was deposited at the substrate temperature of 250 degreesC and operation gas pressure of 0.8 Pa. (C) 2003 Elsevier Science B.V. All rights reserved.